FIG. 4.

The lacR lacF double mutant shows wild-type growth in succinate-plus-raffinose medium. (A) lacF mutants grow very slowly on lactose. The indicated strains were grown in M9 minimal medium containing lactose as the sole source of carbon. OD₄₁₅, optical density at 415 nm. (B) Succinate-mediated diauxie of α-galactoside utilization is restored in a lacR lacF double mutant. The indicated strains were grown in M9 minimal medium containing 0.05% succinate plus 0.1% raffinose. The lacR mutant failed to undergo diauxic growth, whereas the lacR lacF double mutant exhibited diauxic growth which was indistinguishable from that of wild-type (wt) strain Rm1021.